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A Novel Model for Describing Rail Weld Irregularities and Predicting Wheel-Rail Forces Using a Machine Learning Approach

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Computer Modeling in Engineering & Sciences 2025年第1期142卷 555-577页

作者： linlin sun Zihui Wang Shukun Cui Ziquan Yan Weiping Hu Qingchun Meng State Key Laboratory of High-Speed Railway Track System China Academy of Railway Sciences Corporation LimitedBeijing100081China Railway Engineering Research Institute China Academy of Railway Sciences Corporation LimitedBeijing100081China School of Aeronautic Science and Engineering Beihang UniversityBeijing100191China

Rail weld irregularities are one of the primary excitation sources for vehicle-track interaction dynamics in modern high-speed *** can cause significant wheel-rail dynamic interactions,leading to wheel-rail noise,component damage,and *** researchers have employed the vehicle-track interaction dynamic model to study the dynamic interactions between wheel and rail induced by rail weld geometry ***,the cosine wave model used to simulate rail weld irregularities mainly focuses on the maximum value and neglects the geometric *** this study,novel theoretical models were developed for three categories of rail weld irregularities,based on measurements of the high-speed railway from Beijing to *** vertical dynamic forces in the time and frequency domains were compared under different running *** forces generated by the rail weld irregularities that were measured and modeled,respectively,were compared to validate the accuracy of the proposed ***,based on the numerical study,the impact force due to rail weld irrregularity is modeled using an Artificial Neural Network(ANN),and the optimum combination of parameters for this model is *** results showed that the proposed model provided a more accurate wheel/rail dynamic evaluation caused by rail weld irregularities than that established in the *** ANN model used in this paper can effectively predict the impact force due to rail weld irrregularity while reducing the computation time.

关键词： Rail weld irregularity high-speed railway vehicle-track coupled dynamics wheel/rail dynamic vertical force artificial neural networks

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Semi-analytical Modeling of the Influence of Macro Bending Effects on Micro Contact-Inhomogeneity Problems

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Acta Mechanica Solida Sinica 2023年第6期36卷 860-874页

作者： Jinran Li linlin sun Ning Zhao Pu Li School of Mechanical Engineering Northwestern Polytechnical UniversityXi’an 710072China Key Laboratory of Road Construction Technology and Equipment of the Ministry of Education Chang’an UniversityXi’an 710064China Shaanxi Key Laboratory of Gear Transmissions Xi’an 710072China School of Science Harbin Institute of TechnologyShenzhen 518055China

This study examines the effects of macroscopic bending and microscopic contact loading in inhomogeneous materials using a semi-analytical model based on Eshelby’s equivalent inclusion *** model accounts for bending effects through the beam theory,with bending stress included in the Eshelby’s equivalent inclusion *** macroscopic displacement resulting from bending effects is incorporated into the microscopic contact solver,and the final displacement is determined using the conjugate gradient method in an iterative *** efficiency can be improved by incorporating the discrete convolution and fast Fourier *** core scheme is validated using the finite element method,yielding accurate and efficient results for bending-contact problems in inhomogeneous *** reveal the interplay between bending,contact loading,and inhomogeneity,as stress around the inhomogeneity alters and the stress concentration area expands under increasing bending ***,low-magnitude negative bending moments reduce both contact pressure and stress around the *** position where inhomogeneities are least affected shifts from the neutral surface depending on the coupling *** model provides a valuable bridge for connecting the macroscopic bending effect and microscale contact-inhomogeneity problems by visualizing stress fields and assessing pressure distributions.

关键词： Contact analysis Bending effects Inhomogeneity Equivalent inclusion method Semi-analytical model

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The boundary value problem for the mean field equation on a compact Riemann surface

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Science China Mathematics 2023年第1期66卷 115-142页

作者： Jiayu Li linlin sun Yunyan Yang School of Mathematical Sciences University of Science and Technology of ChinaHefei 230026China School of Mathematics and Statistics Wuhan UniversityWuhan 430072China School of Mathematics Renmin Universityof ChinaBeijing100872China

Let(Σ,g)be a compact Riemann surface with smooth boundary■Σ,Δ_(g) be the Laplace-Beltrami operator,and h be a positive smooth *** a min-max scheme introduced by Djadli and Malchiodi(2008)and Djadli(2008),we prove that ifΣis non-contractible,then for anyρ∈(8kπ,8(k+1)π)with k∈N^(*),the mean field equation{Δgu=ρhe^(u)/∫∑he^(u)dv_(g)in∑,u=0 on■∑has a *** generalizes earlier existence results of Ding et al.(Ann Inst H PoincaréAnal Non Linéaire,1999)and Chen and Lin(2003)in the Euclidean *** we consider the corresponding Neumann boundary value *** h is a positive smooth function,then for anyρ∈(4kπ,4(k+1)π)with k∈N^(*),the mean field equation{Δgu=ρhe^(u)/∫_(∑)he^(u)dv_(g)-1/|∑|in∑,■u/■v=0 on■∑has a solution,where v denotes the unit normal outward vector on ■Σ.Note that in this case we do not require the surface to be non-contractible.

关键词： mean field equation topological method min-max scheme

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Tension-Torsion High-Cycle Fatigue Life Prediction of 2A12-T4 Aluminium Alloy by Considering the Anisotropic Damage:Model, Parameter Identification, and Numerical Implementation

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Acta Mechanica Solida Sinica 2016年第4期29卷 391-406页

作者： linlin sun Miao Zhang Weiping Hu Qingchun Meng Institute of Solid Mechanics School of Aeronautic Science and Engineering Beihang University Institute of Manned Space System Engineering China Academy of Space Technology

To consider the anisotropic damage in fatigue, an improved boom-panel model is presented to simulate a representative volume element (RVE) in the framework of continuum damage mechanics. The anisotropic damage state of the RVE is described by the continuity extents of booms and panels, whose damage evolutions are assumed to be isotropic. The numerical implementation is proposed on the basis of damage mechanics and the finite element method. Finally, the approach is applied to the fatigue life prediction of 2A12-T4 aluminium alloy specimen under cyclic loading of tension-torsion. The results indicate a good agreement with the experimental data.

关键词： boom-panel model anisotropic damage fatigue tension-torsion life prediction

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A simple aptamer molecular beacon assay for rapid detection of aflatoxin B1

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Chinese Chemical Letters 2019年第5期30卷 1017-1020页

作者： Chao Wang linlin sun Qiang Zhao State Key Laboratory of Environmental Chemistry and Ecotoxicology Research Center for Eco-Environmental SciencesChinese Academy of SciencesBeijing 100085China University of Chinese Academy of Sciences Beijing 100049China

Aflatoxin B1(AFB1)is a highly toxic mycotoxin,and rapid and sensitive detection of AFB1 is in demand for food safety and environmental *** we described a simple aptamer molecular beacon assay for rapid detection of aflatoxin B1(AFB1)by using an aptamer with a fluorescein(FAM)label at the 50 end and a fluorescence quencher(black hole quencher 1,BHQ1)at the 30 *** the presence of AFB1,the aptamer probe bound with AFB1 and induced a hairpin structure,drawing FAM and BHQ1 into close proximity and leading to fluorescence *** assay allowed for a detection limit of 3.9 nmol/L and a dynamic range from 3.9 nmol/L to 4 mmol/*** test showed other mycotoxins including ochratoxin A,ochratoxin B,fumonisin B1,fumonisin B2,and zearalenone had negligible influence on detection of ***1 spiked in diluted liquor wine,methanol,or corn flour samples was successfully detected by using this aptamer probe,and the assay showed potential for real sample analysis.

关键词： Aptamer Aflatoxin B1 Fluorescence Molecular beacons Mycotoxin Sensor

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Simultaneous optical and electrochemical recording of single nanoparticle electrochemistry

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Nano Research 2017年第5期10卷 1740-1748页

作者： linlin sun Yimin Fang Zhimin Li Wei Wang Hongyuan Chen State Key Laboratory of Analytical Chemistry for Life Science School of Chemistry and Chemical Engineering Nanjing UniversityNanjing 210093 China

Single nanoparticle collisions have become popular for studying the electro- chemical activity of single nanoparticles by determining the transient current during stochastic collisions with the electrode surface. However, if only the electrochemical current is measured, it remains challenging to identify and characterize the individual particle that is responsible for a specific current peak in a collision event; this hampers the understanding of the structure-activity relationship. Herein, we report simultaneous optical and electrochemical recording of a single nanoparticle collision; the electrochemical signal corresponds with the activity of a single nanoparticle, and the optical signal reveals the size and location of the same nanoparticle. Consequently, the structure （optical signal）- activity （electrochemical signal） relationship can be elucidated at the single nanoparticle level; this has implications for various applications including batteries, electrocatalysts, and electrochemical sensors. In addition, our previous studies have suggested an optical-to-electrochemical conversion model to independently calculate the electron transfer rate of single nanopartides from the optical signal. The simultaneous optical and electrochemical recording achieved in the present work enables direct and quantitative validation of the optical-to-electrochemical conversion model.

关键词： single nanoparticlecollision surface plasmonresonance microscopy plasmonics-basedelectrochemicalmicroscopy Ag nanoparticles

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The opportunistic relaying scheme design and symbol error rate analysis for PLC networks in smart homes

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Science China(Information Sciences) 2021年第8期64卷 250-252页

作者： linlin sun Jiahui YAN Yuwen QIAN Feng SHU Xiangwei ZHOU The School of Electronic and Optical Engineering Nanjing University of Science and Technology The Division of Electrical and Computer Engineering Louisiana State University

Dear editor,Power line communication(PLC) is treated as a retrofit technology, transmitting messages via conductors without extra infrastructure, which reduces the cost of implementation and maintenance [1]. Therefore, PLC is extensively adopted in smart grid applications. However, PLC encounters a hostile communication environment caused by the fast signal attenuation and severe impulsive noise [2].

关键词： SER The opportunistic relaying scheme design and symbol error rate analysis for PLC networks in smart homes

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Evaluating the Origin Intensity Factor in the Singular Boundary Method for Three-Dimensional Dirichlet Problems

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Advances in Applied Mathematics and Mechanics 2017年第6期9卷 1289-1311页

作者： linlin sun Wen Chen Alexander H-D.Cheng State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering International Center for Simulation Software in Engineering and SciencesCollege of Mechanics and MaterialsHohai UniversityNanjing 210098China Department of Computational Science and Statistics School of ScienceNantong UniversityNantongJiangsu 226019China School of Engineering University of MississippiUniversityMS 38677USA

In this paper,a new formulation is proposed to evaluate the origin intensity factors(OIFs)in the singular boundary method(SBM)for solving 3D potential problems with Dirichlet boundary *** SBM is a strong-form boundary discretization collocation technique and is mathematically simple,easy-to-program,and free of *** crucial step in the implementation of the SBM is to determine the OIFs which isolate the singularities of the fundamental ***,the inverse interpolation technique(IIT)is adopted to calculate the OIFs on Dirichlet boundary,which is time consuming for large-scale *** recent years,the new methodology has been developed to efficiently calculate the OIFs on Neumann boundary,but the Dirichlet problem remains an open *** study employs the subtracting and adding-back technique based on the integration of the fundamental solution over the whole boundary to develop a new formulation of the OIFs on 3D Dirichlet *** problems with varied domain shapes and boundary conditions are carried out to validate the effectiveness and feasibility of the proposed scheme in comparison with the SBM based on inverse interpolation technique,the method of fundamental solutions,and the boundary element method.

关键词： Origin intensity factors singular boundarymethod boundary-typemeshlessmethod potential problem fundamental solution

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Machine-learning-based high-resolution DOA measurement and robust directional modulation for hybrid analog-digital massive MIMO transceiver

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Science China(Information Sciences) 2020年第8期63卷 21-38页

作者： Zhihong ZHUANG Ling XU Jiayu LI Jinsong HU linlin sun Feng SHU Jiangzhou WANG School of Electronic and Optical Engineering Nanjing University of Science and Technology The College of Physics and Information Fuzhou University School of Engineering and Digital Arts University of Kent

At hybrid analog-digital(HAD) transceiver, an improved HAD estimation of signal parameters via rotational invariance techniques(ESPRIT), called I-HAD-ESPRIT, is proposed to measure the direction of arrival(DOA) of a desired user, where the phase ambiguity due to HAD structure is dealt with ***, a machine-learning(ML) framework is proposed to improve the precision of measuring ***, we find that the probability density function(PDF) of DOA measurement error(DOAME) can be approximated as a Gaussian distribution by the histogram method in ML. Then, a slightly large training data set(TDS) and a relatively small real-time set(RTS) of DOA are formed to predict the mean and variance of DOA/DOAME in the training stage and real-time stage, respectively. To improve the precisions of DOA/DOAME, three weight combiners are proposed to combine the-maximum-likelihood-learning outputs of TDS and RTS. Using the mean and variance of DOA/DOAME, their PDFs can be given directly, and we propose a robust beamformer for directional modulation(DM) transmitter with HAD by fully exploiting the PDF of DOA/DOAME, especially a robust analog beamformer on RF chain. Simulation results show that:(1) the proposed I-HAD-ESPRIT can achieve the HAD Cramer-Rao lower bound(CRLB);(2) the proposed ML framework performs much better than the corresponding real-time one without training stage;(3) the proposed robust DM transmitter can perform better than the corresponding non-robust ones in terms of secrecy rate.

关键词： hybrid analog and digital ESPRIT statistical learning DM robust precoder

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Dirac-harmonic maps with the trivial index

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Science China Mathematics 2024年

作者： Jürgen Jost linlin sun Jingyong Zhu Max Planck Institute for Mathematics in the Sciences School of Mathematics and Statistics Guangxi Normal University School of Mathematics Sichuan University

For a homotopy class [u] of maps between a closed Riemannian manifold M and a general manifold N, we want to find a Dirac-harmonic map with the map component in the given homotopy class. Most known results require the index to be nontrivial. When the index is trivial, the few known results are all constructive and produce uncoupled solutions. In this paper, we define a new quantity. As a byproduct of proving the homotopy invariance of this new quantity, we find a new simple proof for the fact that all the Dirac-harmonic spheres in surfaces are uncoupled. More importantly, by using the homotopy invariance of this new quantity,we prove the existence of Dirac-harmonic maps from manifolds in the trivial index case. In particular, when the domain is a closed Riemann surface, we prove the short-time existence of the α-Dirac-harmonic map flow in the trivial index case. Together with the density of the minimal kernel, we get an existence result for Dirac-harmonic maps from closed Riemann surfaces to K¨ahler manifolds, which extends the previous result of the first and third authors. This establishes a general existence theory for Dirac-harmonic maps in the context of the trivial index.

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